This year, Selena Gomez has released a handful of really solid hits, including the understated bangers "Bad Liar" and "Fetish" and the electronic Kygo collab, "It Ain't Me." Normally, this would've been her summer to promote these songs endlessly, perhaps even hitting some awards show stages for memorable performances.

But in an Instagram post shared Thursday morning (September 14), Selena revealed why she's been keeping out of the spotlight lately: "I found out I needed to get a kidney transplant due to my Lupus and was recovering. It was what I needed to do for my overall health."

The first pic, which shows Selena hooked up to all sorts of machines in a hospital bed, nevertheless displays her smiling. That might be because she's next to her friend Francia Raisa, star of Secret Life of the American Teenager, who donated one of her kidneys to Selena.

"There aren't words to describe how I can possibly thank my beautiful friend Francia Raisa," Selena wrote in her Instagram note. "She gave me the ultimate gift and sacrifice by donating her kidney to me. I am incredibly blessed. I love you so much sis."

Selena also hinted that we'd be learning more details soon, and she also encouraged people to read up on the "misunderstood" autoimmune disease by visiting the Lupus Research Alliance website.

"I honestly look forward to sharing with you, soon my journey through these past several months as I have always wanted to do with you," Selena wrote. "Until then I want to publicly thank my family and incredible team of doctors for everything they have done for me prior to and post-surgery."

Selena's been open about her struggle with lupus, and she told MTV News in June why she kept a hospital bracelet on for the "Bar Liar" music video. Watch her discuss that below.